Digital Room Thermometer: Recommendations

Hattie627

As previously indicated, I am trying to get up to speed on domestic energy-saving from a very low knowledge start.

I inherited an old room thermometer from my late dad. I reckon it is quite old. It currently hangs in my kitchen. It is labelled "Factory Thermometer" and "Factories Act 1961 section 3" and has the name Zeal on it ("Made in England"). It has a scale with temp shown in F on the left and C on the right. It seems quite accurate but it's an effort to read.

In the interests of being more energy-saving conscious, I was thinking of entering the digital age and investing in a digital room thermometer. First question is, are the worth having and are they accurate? Should I just continue with the old one or would the investment in a new one be worth it? Second question is, there are so many on Amazon and I haven't a clue how much I should be paying for one. Has anyone got any advice, either as to specific models to recommend or a rough idea of how much a reliable one should cost?

Thank you in advance. Really appreciate any advice which anyone can give.

JSHarris

Zeal make excellent thermometers, lab grade and almost certainly more accurate than a consumer-grade digital thermometer.  Nothing to go wrong with them, either, and they don't need power, so in a tiny way they are more energy efficient.  As long as you can read the temperature on it OK I would keep it, personally.

Hattie627

JSHarris said:

Zeal make excellent thermometers, lab grade and almost certainly more accurate than a consumer-grade digital thermometer.  Nothing to go wrong with them, either, and they don't need power, so in a tiny way they are more energy efficient.  As long as you can read the temperature on it OK I would keep it, personally.

Thank you, very helpful. Yes, I can read the temperature but the red line is faintish, so it does require more effort than a bright, shiny digital read-out would require, so (inevitably) it is not checked as often as might be desirable. As to accuracy, no issues obvious.

QrizB

I suppose it comes down to a question of "what are you trying to measure?"

Do you want to know the precise temperature of your room, or do you want to know whether it's warmer or cooler than it was yesterday?

A precise thermometer is likely to be expensive, but even a cheap thermometer should give you fairly accurate relative readings.

Gerry1

TL;DR: Lots of good stuff around and often cheap as chips.

I bought one of these from the middle aisle of Aldi or Lidl, £9.99 IIRC.

https://www.ebay.co.uk/p/9058164469?iid=266570894079

Not sure it's a current model but it's accurate, shows humidity which is very useful and whether the readings are increasing.

There are many similar products around, some with external sensors either wired or radio.  Some also store maximum and minimum readings.

Stubod

I got a couple of "Thermo pro TP357" from Amazon, about £8 each. Really good, and you can download the graphs to a smart phone / tablet which gives you 24 / weekly / annual results.......

...just a shame it won't let you import the data to excel (or similar), but they seem to work really well and were easy to set up and download the app...

JSHarris

QrizB said:

I suppose it comes down to a question of "what are you trying to measure?"

Do you want to know the precise temperature of your room, or do you want to know whether it's warmer or cooler than it was yesterday?

A precise thermometer is likely to be expensive, but even a cheap thermometer should give you fairly accurate relative readings.

Very true, I have a pair of very accurate (and expensive!) Zeal nitrogen filled lab thermometers that I use as references:

Comparing the readings from these with even fairly expensive digital temperature display devices has been surprising.  For example, our heat recovery ventilation system controller has a digital room temperature display.  This unit wasn't cheap (the thing cost over £4,000), yet the digital temperature display has a +1.8°C error.  The digital thermostat that controls our heating is similar, that has an error of +0.9°C.

Using relatively cheap digital thermometers for a relative measurement is probably OK, my limited experience shows they seem to be reasonably linear in response, they just tend to have calibration offset errors.

In my home automation system I have a number of temperature sensors embedded in the walls and floor, in the heating flow and return pipes, in the ventilation ducts and measuring the room and outside temperature.  These all had offset errors as supplied (but were very linear), but this offset can be easily corrected in software (although it was a faff leaving a dozen or so sensors in an insulated tub of water to get them all to stabilise to the same temperature to calibrate them).

Ectophile

I'd recommend getting a combined thermometer and hygrometer.  There are any number of them available on the home shopping sites, including the one named after a large South American river.  They aren't expensive.

That way you can not only tell what the temperature is, but also if the air is too damp or too dry.

Reed_Richards

Ectophile said:

I'd recommend getting a combined thermometer and hygrometer.  There are any number of them available on the home shopping sites, including the one named after a large South American river.  They aren't expensive.

That way you can not only tell what the temperature is, but also if the air is too damp or too dry.

I was also going to recommend a combined thermometer and hygrometer.  The one I have is a ThermPro model and mine also has an outdoor unit that communicates wirelessly.  It costs about £20 and has worked fine; I have to change the batteries about once a year.  A version without the outdoor unit costs about £10.